The invention pertains to digital data processing and, more particularly, to networks and methods of operation thereof. The invention has application, for example, in managing storage area networks.
In early computer systems, long-term data storage was typically provided by dedicated storage devices, such as tape and disk drives, connected to a data central computer. Requests to read and write data generated by applications programs were processed by special-purpose input/output routines resident in the computer operating system. With the advent of “time sharing” and other early multiprocessing techniques, multiple users could simultaneously store and access data—albeit only through the dedicated storage devices.
With the rise of the personal computer and workstation in the 1980's, demand by business users led to development of interconnection mechanisms that permitted otherwise independent computers to access data on one another's storage devices. Though computer networks had been known prior to this, they typically permitted only communications, not storage sharing.
The prevalent business network that has emerged is the local area network, typically comprising “client” computers (e.g., individual PCs or workstations) connected by a network to a “server” computer. Unlike the early computing systems in which all processing and storage occurred on a central computer, client computers usually have adequate processor and storage capacity to execute many user applications. However, they often rely on the server computer—and its associated battery of disk drives and storage devices—for other than short-term file storage and for access to shared application and data files.
An information explosion, partially wrought by the rise of the corporate computing and, partially, by the Internet, is spurring further change. Less common are individual servers that reside as independent hubs of storage activity. Often many storage devices are placed on a network or switching fabric that can be accessed by several servers (such as file servers and web servers) which, in turn, service respective groups of clients. Sometimes even individual PCs or workstations are enabled for direct access of the storage devices (though, in most corporate environments such is province of server-class computers) on these so-called “storage area networks” or (SANs).
The management of SANs typically involves automated discovery of the SAN physical topology, e.g., the interconnections and relationships among host computers (e.g., servers), storage devices and other components participating in the SAN, and their configurations. This can be accomplished through in-band discovery—that is, by querying designated addresses in the devices or on the network or fabric that connects them. However, the information provided by most in-band discovery mechanisms is limited to how the components' respective physical network end-points, or ports, are connected. Referring to FIG. 1, for example, in-band discovery might reveal that there are a number of ports connected into the SAN fabric, but it will not reveal in which of those host computers (Host 1, Host 2 or Host 3) the ports are contained.
The art has taken steps toward facilitating SAN management, e.g., in instances where only in-band discovery is possible. An emerging industry standard T11/FC-GS-3 of the American National Standard of Accredited Standards Committee NCITS, for example, proposes a system of “platform” registration, wherein each component (or platform) on a fibre channel fabric registers with a fabric-based service, supplying information such as component name and type, contained fibre channel ports, management addresses, description and location. That information is made available to the other components which can use it, e.g., for storage area network management.
Though platform registration can facilitate SAN management, many SAN components do not practice it. This will likely be the state of affairs for many years to come as manufacturers bring their fibre channel and non-fibre channel (e.g., iSCSI) product lines into conformity with registrations standards such as those provided under T11/FC-GS-3.